Cooling fan is not coming on without AC on

Tiny
CHARLIE1229
  • MEMBER
  • 1998 PONTIAC GRAND PRIX
  • 170,000 MILES
We have a 1998 Pontiac Grand Prix. Cooling fans work when AC is on, but they will not turn on when engine gets to 230 degrees Fahrenheit without the AC on. We have swapped relays, changed the coolant temp sensor. Still no luck. Anything we are missing? We know the coolant 1 and coolant 2 relays are working because the fans come on with the AC. Not sure of the function of the other NO/NC relay.
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Thursday, December 22nd, 2011 AT 12:48 AM

7 Replies

Tiny
SATURNTECH9
  • EXPERT
Have you checked the coolant temp sensor yet?
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Thursday, December 22nd, 2011 AT 12:55 AM
Tiny
CHARLIE1229
  • MEMBER
Yes I have already replaced it
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Thursday, December 22nd, 2011 AT 2:56 AM
Tiny
SATURNTECH9
  • EXPERT
What colors were the wires going to it?
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Thursday, December 22nd, 2011 AT 6:50 AM
Tiny
WRENCHTECH
  • EXPERT
Let me jump in here.

Your car is responding exactly the way it was designed to. It was programmed to come on at 230 without A/C

Here is a description of the circuit from the service manual

ELECTRIC ENGINE COOLING FAN AND RELAY
These vehicles use 2,360 mm (14.2 inch) cooling fans to aid air flow through the radiator. Electric motors drive the cooling fans. These motors are attached to the radiator. Motor size varies with each engine option.
A coolant temperature switch activates the fan motors. This switch regulates voltage to the cooling fan relay. This switch operates the fan whenever the engine coolant temperature exceeds 11O C (230 F). For location and diagnosis, refer to Diagrams. A transducer can also activate the circuit, depending on the A/C compressor head pressure going to the condenser.
The engine cooling fan relays provide the high current required for the cooling fan motors using a low current signal coming from the Powertrain Control Module (PCM). This signal is a function of various inputs.
Refer to Diagrams for further information and diagnosis of the cooling fan relay.
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Thursday, December 22nd, 2011 AT 11:00 AM
Tiny
SATURNTECH9
  • EXPERT
Thanks for the jump in wrenchtech.
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Thursday, December 22nd, 2011 AT 10:22 PM
Tiny
WRENCHTECH
  • EXPERT
No problem. Happy Holidays
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Thursday, December 22nd, 2011 AT 10:28 PM
Tiny
SATURNTECH9
  • EXPERT
You too my friend.
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Thursday, December 22nd, 2011 AT 10:34 PM

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